The present invention relates to optical power conversion, and more particularly to a means for converting optical power to a regulated direct current (D.C.) voltage using a single photodetector while providing data communications.
In optical power conversion a laser diode commonly is used as a power source for the transmission of optical energy. At the reception end a photodetector is used to convert the optical energy to electrical energy. The transmission medium between the laser diode and photodetector typically is an optical fiber. The voltage generated across the photodetector is slightly less than one volt. Since most electrical circuits need a minimum of 2.5-5.0 volts to operate, a plurality of photodetectors are coupled in series to provide at least a 5.0 volt output. With the photodetectors in series, the photodetector that receives the lowest amount of light sets the current output for all of the photodetectors. Thus the efficiency of energy transfer is less than maximum since it is very difficult to provide uniform illumination for all of the photodetectors.
An alternative type of photodetector is in the form of a circle having a plurality of pie-shaped segments that are coupled in series. This is a very expensive component, but provides a configuration for which it is easier to provide uniform illumination for all segments. However, due to the differences in quantum efficiencies between the segments, the power transfer efficiency is still less than optimum.
What is desired is an optical power conversion means for converting optical energy to electrical energy with optimum power transfer efficiency.